Electronic components, especially semiconductors components such as transistors and chips are prone to failure or malfunction at high temperatures. The removal of heat from electronic components is a perpetual problem in electronics industry. The electronic component is typically mounted on a thermal dissipation member such as a cold plate or heat sink for heat removal. Cold plates and heat sinks are made of thermally conductive materials that draw heat away from the electronic component to which they are attached. Typically, the thermal coefficient of expansion of the electronic component and the thermal coefficient of expansion of the heat sink are not the same. During a thermal cycle, when the electronic component heats up and subsequently cools down, the difference in thermal coefficient of expansion between the electronic component (chip) and the heat sink causes differential expansion of the surfaces of the chip and the heat sink. This differential expansion may lead to the disengagement of the thermal and mechanical contact of the surfaces or to the fracture of the chip in case of a solid contact. The heat sink cannot provide thermal dissipation if it is not in thermal and mechanical contact with the surface of the chip. One approach for avoiding such disengagement is to glue or solder the surfaces together, but this may lead to the buildup of high stresses in the interface between the surfaces. Another approach for preventing stress buildup in the interface involves using a thick layer of thermal paste. A thick layer of thermal paste placed between the surfaces allows for relative movements of the surfaces of the chip and the heat sink. For example, a thermal paste about 75 microns thick provides lateral and vertical movement of more than 10 microns between the surfaces. However, the thermal resistance of the interface scales with the thickness of the thermal paste between the surfaces. This thermal resistance component is typically the dominant resistance on the path from the electronic component to the heat sink in most single chip and multi-chip modules (with other thermal resistance components being conductive thermal resistance of the chip, spreading resistance of any thermal spreader and convective thermal resistance of a cold plate or a heat sink). For example, the use of thermal paste of thickness 75 microns and a bulk thermal resistance of ˜3.5 W/mK will introduce a thermal resistance of about 0.2 Kcm2/W. If the thermal resistance is too high, then the interface will not conduct the heat effectively.
Thus, there is a need for a thermal interface that prevents stress buildup between the surfaces of a chip and a heat sink, ensures a reliable thermal and mechanical contact, and minimizes the resistance to thermal conduction.